Burnishing head



Dec. 8, 1959 2,915,809

w. F. E GGER, JR

BURNISHING HEAD Filed April 28, 1955 3 Sheets-Sheet l INVENTOR. W41??? E 56652 J2.

Dec. 8, 1959 w. F. EGGER, JR

BURNISHING HEAD Filed April 28, 1955 3 Sheets-Sheet 3 (3 9 I 9 INVENTOR- zrmeA am United States Patent G BURNISHING HEAD Walter F. Egger, Jr., Beachwood Village, Ohio Application April 28, 1955, Serial No. 504,520

9 Claims. (Cl. 2990) This invention relates as indicated to a new type of burnishing head and, more particularly, to a device of this nature for the finishing of crankshaft bearing surfaces and the like.

It is a primary object of the invention to eliminate the costly use of abrasive cloth or paper in conventional crankshaft finishing practice by providing a roller type of burnishing head of an improved design which meets those problems incident to working a reduced cylindrical section of a workpiece, such as presented by the crankpins and journals of a crankshaft wherein the same are bounded by the projecting radial surfaces of the throws or checks of the shaft.

Another object is to provide a tool assembly especially suited for polishing surfaces of a workpiece which are not fully accessible in the respect noted by employing in such assembly rolling elements so mounted as to effect working of the surface to be finished over substantially the entire extent thereof without traversing movement.

It is also an object of the invention to provide a tool of the type indicated which effects polishing of the Work surface by combined rolling and sliding actions.

An additional object is to provide a burnishing head comprising a plurality of rolling members so arranged and mounted in relation to the workpiece as to be stable in operation while effective to work the metal axially as well as peripherally.

It is a further object to provide rolling shoes of a construction enabling the same to be readily and economically incorporated in a crankshaft finishing machine of the type conventionally employed for lapping all the crankpins and journals simultaneously, thereby to permit the conversion of a standard machine to accomplish the improved results of the invention without expensive modification or rebuilding of such existing apparatus.

Other objects and advantages of the invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In .said annexed drawings:

Fig. 1 is a side elevational view, partly in section and partly broken, of a crankshaft finishing head equipped with rolling shoes in accordance with the invention;

Fig. 2 is a view in elevation, to an enlarged scale, of one such shoe;

Fig. 3 is a view in elevation of the front or working side of this shoe;

Fig. 4 is a sectional view taken on the plane of the line 4-4 in Fig. 2;

Fig. 5 is a fragmentary illustration of the lower portion 0 of the head equipped with shoes of a slightly different 7 2,915,809 Patented Dec. 8, 1959,

Fig. 6 is an enlarged side elevational view of this further form of rolling shoe;

Fig. 7 is a sectional view taken on the plane of line 7-7 in Fig. 6;

Fig. 8 is a sectional view taken on the plane of the line 8-8 in Fig. 6; and

Fig. 9 is a fragmentary plan view of an adjustable interlock with which both forms of the shoe may be provided.

Referring now to the drawings in detail, and especially to Fig. 1, the support and guiding structure of the head illustrated is of conventional type, this particular assembly being employed in the crankshaft lapping machines supplied by A. P. Schraner Co. of Cleveland, Ohio. As indicated in the above, it is one of the objects of my invention to permit the ready conversion of existing machines of this type, which normally would comprise a number of standard lapping heads depending upon the number of the bearing surfaces of the crankshaft to be finished, for burnishing by means of rolling elements, and, to this end, the conventional structure has been utilized as much as possible.

The head thus comprises the usual cylinder 1 within which a piston 2 having an elongated, downwardly extending piston rod 3 is reciprocable. Hydraulic couplings 4 and 5 provide communication between the cylinder bore and hoses 6 and 7 respectively at the ends of the cylinder for fluid drive of the piston in known manner. The cylinder at its upper end is closed by a cap 8 and a head guide 9 extends thereabove for engagement about a head guide bar 1%. A slide 11 is attached to the lower end of the cylinder 1 and projects downwardly through two laterally spaced guide arms 12 mounted on the frame of the machine by a bracket 13.

Piston rod 3 extends into the guide arm assembly and has a center block 14 attached at its lower end. Pivotally secured to the block are toggle links 15 extending to opposite sides and being respectively connected pivotally at their outer ends to a pair of opposed clamping fingers 16.

The structure further comprises standard guide arm clampingmeans for locking the slide 11 in non-operative condition, such means comprising front and rear shafts 17 and 18 having lock nuts 19 and 2t) threaded respectively thereon. The front nut is provided with a lock screw 21, while the nut 26 has a lock screw 22 operatively associated therewith in a similar manner. Lock levers 23 secured to the front and rear shafts project above the arms of the guide assembly and are pivotally interconnected at their upper ends by means of links 24 and an adjusting nut 25. Such levers are actuable to draw the guide arms tightly together against the slide in one condition and to separate the arms so that the slide may oscillate in another.

That much of the head construction described above is conventional and, therefore, does not require to be set forth in any more detail. With regard to operation, it will be apparent that the hydraulic piston-cylinder unit is operable to cause the clamping fingers 16 to open and close for insertion therebctween and removal of the crankshaft. It will be further understood that a complete machine will comprise a plurality of heads each adapted to perform work upon one of the bearing surfaces of the crankshaft and all being mounted in a suitable frame including means for chucking and rotating the shaft,

In lieu of the usual abrasive material holders used with such standard head structure, I provide a pair of rolling shoes indicated generally at 26, one being mounted on each of the toggle-actuated clamping fingers. Each of these shoes comprises, as most clearly shown in Figs. 2 to' 4, a body 27 in the form of a generally rectangular block, the maximum width of which is not greater, and is preferably slightly less, than the width of the bearing surface to be polished. The body is arranged with its longer extent vertical in the working position of the shoe and is formed with a slot 28 in its rear face for reception of the lower end of the associated clamping finger 16. The two such parts are held engaged by means of a pin 29 which extends transversely through the slotted portion of the body and through the end portion of the clamping finger fitted therewithin.

The shoe body 27 is of uniformly reduced width forwardly of its longitudinally slotted portion, such reduced portion being indicated at 30, and the front or inner face thereof is shaped to have a transversely arcuate recess 31 intermediate the top and bottom portions of the body. Two transverse slots 32 are formed in the curved face of the recess 31, extending completely across the body like the latter, in circularly spaced-apart relation. Such slots are of a section which is a major portion of a circle so that the passages provided thereby are enlarged inwardly of the resulting openings 33 in the recess face.

The reduced portion 30 of the body is further provided with a series of four stepped transverse bores 34 each of which is enlarged at the respective ends 35 thereof. These bores are so positioned that two of them are circularly spaced about and behind each of the semicylindrical slots 32, on axes parallel to the axis of the latter, with their enlarged end portions 35 intersecting the thus associated slot so as to provide limited communication therebetween. A roller bearing 36 of conventional type is received within each bore end portion 35, the coaxial pairs of such bearings being mounted on shafts 37 in the bores 34 and the outer races of the bearings projecting slightly into the adjacent slot 32. The ends of such shafts extend beyond the sides of the body portion 359 and are supported in side plates 38 attached to such portion and occupying substantially exactly the spaces formed by the reduction. Such plates, which thus overlie the outer ends of the bearings 36, are formed at their inner edges similarly as the inner face of the body so as to present a corresponding profile and have recesses 39 forming exact continuations of the body recesses 32.

Disposed with some peripheral clearance in each slot 32 is a cylindrical roller 40 having a helical burnishing land 41 on its outer surface which extends from one end to the other of the roller. Each such roller as thus received in its slot 32 projects outwardly beyond the curved Wall of recess 31 a predetermined extent through the communicating opening 33 for contact with the work, the roller being prevented from moving completely outwardly due to the restriction at such opening. The rollers 40 are contacted inwardly of the body by those portions of the associated four roller bearings 36 which project into the slots 32, whereby the bearings rotatably back the rollers. Accordingly, it will be seen that each roller 49 is free to rotate in response to its engagement with the work surface, the workpiece being driven in operation of the machine. When thus engaged with the work, the normally floating rollers are positioned and supported by the work and the associated roller bearings which together provide three peripherally spaced contact regions for each roller.

In order to prevent the rollers from shifting or moving axially out of the slots 32, each roller 40 is provided with a circumferential groove 42 adjacent one end in the portion thereof received within the side plate recess 39 at such end and of a width which is approximately one half of the width of the plate. The latter is formed with an inner shoulder 43 in such recess 39 which projects into the groove, the engagement permitting rotation of the roller but not endwise Withdrawal thereof. As illustrated, the two burnishing rollers of the shoe are reversed with respect to one another, that is, they are thus engaged with the side plates respectively at opposite sides of the shoe and the helices of their lands 41 advance in opposite directions. This provides a counter-action of any sidewise thrust and thereby serves to stabilize the shoe when engaged with the Work. When properly centered longitudinally, the rollers project slightly and equally beyond the sides of the completely assembled shoe.

By virtue of the desired mounting of the rollers 40, the same are effective over their entire axial extent and, accordingly, are capable of engaging in working relation substantially the entire width of the bearing surface to be polished. The four such rollers of the head when applied to the rotating bearing surface work the metal both axially and circumferentially, slight waves or ripples in the surface metal being set up to produce the desired finishing. The contact pressure is, of course, derived from the action of the clamping fingers on which the rolling shoes are mounted.

In Figs. 5 to 8, I have illustrated a modified form of shoe similarly designed for working the bearing metal but by means of conical, rather than cylindrical, rolling members. Each such modified shoe 46 mounts an upper conical roller 47 having a rounded helical peripheral rib 48 and a lower conical roller 49, having a similar rib 59, at the inner face or side thereof, the body being recessed as indicated at 51 between the roller mounting portions of the same. Roller 47 is partially received within an angular slot 52 of the shoe and supported on a shaft 53 at an angle to and in the plane of the normal axis of the work. The lower roller 49 is similarly but reversely mounted in a slot 54 on a shaft 55.

As illustrated, the peripheral extent of each conical roller is approximately one-half of the Width of the bearing surface to be finished, such surface being designated by the dashed line 56 in Figs. 7 and 8, and the mounting is such that the base portions of the two are disposed at and project slightly beyond the respective sides of the shoe. A bearing sleeve 57, or a suitable roller bearing, is interposed between each roller and its shaft, and the two shafts are locked against rotation in the shoe body. Shaft 53 is thus locked by engagement of a set screw 58 with a flatted portion 59 thereof, while set screw 60 similarly engages the flatted portion 61 of shaft 55 for the same purpose. Each shoe 46 is attached to one of the head clamping fingers 16 in the same manner as the first-described form of shoe.

The complete head, including an opposed pair of the modified shoes 46, provides four such conical rollers each of which contacts and is effective to work approximately one half of the width of the bearing surface. Since the rolling elements are here conical, a combination of rolling action and sliding action will obtain to effect the polishing of such surface. The reversal, or more properly the alternation, of these rollers about the work provides the desired stability against lateral shifting. It will be appreciated by workers in the art that the rollers could be formed with longitudinally concave profiles and mounted so that the line of contact of each with the work will be a portion of a helix, rather than a straight line as obtained with the true conical form, either four complementary rollers of this nature or two adapted each to contact the work surface from end to end being usable in the head.

In all forms of the head, the assembly comprises a pair of opposed and reversed shoes and the work is, accordingly, engaged by the rolling elements of the shoes at a number of spaced points about its periphery for efiicient burnishing. The rolling elements are so formed and/or treated as to have contact surfaces which are harder than the surface to be worked and, in the cylindrical roller assembly, the back-up roller bearings have still harder surfaces further to minimize wear. The invention thus provides durable tool structure which permits crankshafts to be polished more economically than has been possible with the usually employed abrasive cloth and paper having a comparatively much shorter useful life.

The contact pressure of the rolling elements with the work is obtained through the action of the clamping fingers of the head. For purposes of adjustable feed and at the same time to make the head in working relation more rigid, the shoes may be provided with adjustable interlocks at top and bottom, preferably of the tongue and groove type. In Fig. 9, I have illustrated one form of tongue and groove structure usable for the purpose, the tongue here being formed by a socket head set screw 62 threaded into the face of one shoe S and the other shoe S being formed with a groove 63 within which a second socket head set screw 64 is disposed. Lock nuts 65 and 66 are preferably provided to lock the screws in selected positions of adjustment, and it will be seen that by corresponding adjustment of the two screws, the interengagement or the approach of the shoes may be varied.

While the invention has been described in connection with finishing of crankshafts, since this is the principal intended application thereof, it will be apparent that the rolling shoes disclosed may be employed with particular advantage for the burnishing of any workpiece surfaces which are inaccessible in the sense that they are contiguous with substantially radial or right angle surfaces.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a burnishing head, a pair of opposed shoes each of which has a plurality of transverse slots enlarged inwardly cylindrically in its inner face, a cylindrical roller having a helical burnishing land on its outer surface extending from one end to the other thereof disposed rotatably in each such slot, a peripheral portion of each roller projecting through the restricted opening of the slot within which it is disposed, and a plurality of antifriction elements carried by each shoe in engagement with each roller at spaced inner peripheral portions thereof, the length of the rollers being slightly greater than the width of the inner faces of the shoes and the rollers being disposed with their ends projecting beyond the shoes at both sides of the latter.

2. In a burnishing head, a pair of opposed shoes each of which has a plurality of transverse slots enlarged inwardly cylindrically in its inner face, a cylindrical roller having a helical burnishing land on its outer surface extending from one end to the other thereof disposed rotatably in each such slot, a peripheral portion of each roller projecting through the restricted opening of the slot within which it is disposed, a plurality of anti-friction elements carried by each shoe in engagement with each roller at spaced inner peripheral portions thereof, the length of the rollers being slightly greater than the width of the inner faces of the shoes and the rollers being disposed with their ends projecting beyond the shoes at both sides of the latter, and restraining means releasably interengaged with each roller and the shoe mounting the same operative to preclude axial withdrawal of the roller from the shoe.

3. In a burnishing head, a rolling shoe comprising a body in the form of a generally rectangular block, one elongated side of said body being formed with an inwardly arcuate recess, two circularly spaced-apart transverse slots being provided in the curved wall of such ecess, each of said slots being of a section which is the major portion of a circle, a cylindrical roller having a helical burnishing land on its outer surface extending substantially continuously over the complete axial extent thereof rotatably disposed in each such .slot, and stop means interengaged with the shoe body and each roller 6 in the slot housing the latter and intermediate the ends of the roller operative to prevent endwise withdrawal of the same from the shoe, the rollers being of a length slightly greater than the width of the inner face of the shoe.

4. In a burnishing head, a rolling shoe comprising a body in the form of a generally rectangular block, one elongated side thereof being formed with an inwardly arcuate recess, twov circularly spaced-apart transverse slots being provided in the curved wall of such recess, with each such slot being of a section which is the major portion of a circle, and a cylindrical roller having a helical burnishing land on its outer surface extending substantially continuously over the complete axial extent thereof rotatably disposed in each such slot, such rollers being of such relative diameter as to project partially through the slot openings in the recess wall, thereby peripherally to engage the work, and of a length slightly greater than the width of the shoe body, the rollers being disposed with their ends projecting beyond the shoe body at both sides of the same.

5. A rolling shoe comprising a roller having a substantially continuous helical burnishing land on its periphery and extending from one end to the other, a holder having a portion partially encircling said roller along the axis thereof and supporting the same in such manner for rotation, the roller having a length which is greater than the width of the roller and being held with its ends projecting respectively beyond the side limits of said holder, the latter extending substantially at right angles to the roller axis, and an arm connected to said holder in substantially the same plane, the shoe thereby being capable of burnishing a work surface bounded by contiguous normal surfaces over the complete length of such work surface without interference between the holder and arm and such normal surfaces.

6. In a burnishing head, support means, and plural rolling elements mounted for free rotation at inner face portions of said support means generally transversely with respect thereto and projecting laterally therefrom, the projecting and hence exposed surfaces of said rolling elements extending in parallel circularly spaced rela tion, whereby such rolling elements are adapted to engage a cylindrical workpiece simultaneously along a plurality of lines of contact spaced about the periphery thereof, said plural rolling elements being disposed with such laterally projecting surfaces thereof together extending over the entire transverse extent of said support means imd projecting at least slightly beyond both sides of the atter.

7. The combination set forth in claim 6 characterized further in that said rolling elements are cylindrical.

8. The combination set forth in claim 6 characterized further in that said rolling elements are conical.

9. The combination set forth in claim 8 characterized further in that one such conical rolling element is disposed with its laterally projecting surface extending approximately from the transverse center of the support means to a point slightly beyond one side of the latter, and another such conical element extends in reversed relation approximately from such center to a point slightly beyond the other side of the support means.

References Cited in the file of thispatent UNITED STATES PATENTS 162,155 Cook Apr. 20, 1875 365,980 Fairbairn July 5, 1887 1,269,317 Schlegl June 11, 1918 1,373,095 Prossen Mar. 29, 1921 1,434,234 Smith Oct. 31, 1922 1,516,268 Drissner Nov. 18, 1924 1,516,269 Drissner Nov. 18, 1924 (Other references on following page) UNITED STATES PATENTS Ford Aug. 23, 1932 Dunning June 6, 1933 Farr Apr. 16, 1935 Hazelett Mar. 30, 1937 Scribner July 6, 1937 Christrnan Sept. 2, 1941 Johnson Nov. 16, 1948 Walford May 1, 1951 8 Schlitters July 21, 1953 Tack Feb. 14, 1956 FOREIGN PATENTS Great Britain Jan. 30, 1922 Germany Feb. 24, 1912 Italy Apr. 12, 1951 Germany Sept. 24, 1932 France Dec. 14, 1923 

